Toothed shroud centrifugal impeller

ABSTRACT

A centrifugal impeller wherein the peripheral edges of the shrouds include alternate teeth and recesses which are located between adjacent ones of the vane outer ends to be longitudinally along the arcuate impeller vanes.

United States Patent 1191 11] 3,746,467 Buse 1 'July 17, 1973 [54] TOOTHED SHROUI) CENTRIFUGAL 3,128,051 4/1964 Smith .1 416/183 UX IMPELLER 3,221,662 12/1965 White 416/185 x 3,283,829 11/1966 Aumarechal 416/228 UX [75] Inventor: Frederic W- B se, A ento n, Pa. 3,481,531 12/1969 MacArthur ct 8.1 416/236 x [73] Assignee: Ingersoll-Rand Company, New FOREIGN PATENTS OR APPLlCATlONS York 593,899 3 1960 Canada .1 416/228 7,768 0/1910 Great Britain... 415/171 [22] 1971 877,878 9/1961 Great Britain... 416/228 [21] Appl. No; 174,414 979,432 l/1965 Great Britain .1 416/183 Primary Examiner-Everette A. Powell, Jr. 4l6/186r,01l1d6/5?;(2): A'tmmey 1:rank Troidl and Rube" R Paquin [58] Field of Search", [57] ABSTRACT A centrifugal impeller wherein the peripheral edges of 5 References Cited the shrouds include alternate teeth and recesses which UNITED STATES PATENTS are located between adjacent ones of the vane outer 867 069 9,1907 N 416/186 ends to be longitudinally along the arcuate impeller 1 eumann 1,320,031 10 1919 Andrews.... 416/186 x vanes 2,343,714 3/1944 Swenson 415/121 B UX 18 Claims, 4 Drawing Figures Pmmmw v 3 .746.467 I INVENTOR FRED W. BUSE BY 7 ATTORNEY TOOTHED SHROUD CENTRIFUGAL IMPELLER The present invention relates to centrifugal impellers and more specifically to the provision of a new and improved centrifugal impeller particularly constructed and arranged to provide an unusually high head for its diameter.

Conventionally, to increase the head of a centrifugal pump the vane angles of the pump impeller have been varied and/or the diameter of the impeller increased. However, although variation of the impeller vane angles may result in increased head at the upper limits of the pump performance, such does not provide increased head at full capacity where it is usually re quired. Moreover, the necessity for increased impeller diameter is undesirable in that it inherently results in a commensurate increase in the cost of the pump.

An object of the present invention is to provide a new and improved centrifugal impeller which is particularly constructed and arranged to provide an unusually high head for its diameter.

Another object of the invention is to provide a new and improved centrifugal impeller which is particularly constructed and arranged to provide such unusually high head both at the best efficiency point of its operation and at shutoff.

Another object is to provide a new and improved centrifugal impeller which is particularly constructed and arranged to provide such unusually high head without substantial reduction in the hydraulic efficiency of the impeller.

Another object is to provide a new and improved centrifugal impeller which is particularly constructed and arranged to provide such unusually high head without reduction in the hydraulic thrust of the impeller and/or increased noise level of the impeller operation.

Another object is to provide a new and improved centrifugal impeller of the type set forth which is relatively simple and economical in construction.

In accordance with the invention, a centrifugal impeller may comprise a plurality of shrouds having a cavity therebetween and spaced at their peripheries to permit discharge from the cavity, one of the shrouds having an inlet communicating with the cavity centrally thereof, a plurality of vanes in the cavity unitary with the shrouds, the vanes extending from adjacent the inlet towards the peripheries of the shrouds and having outer ends at locations spaced around the peripheries of said shrouds, the vanes therebetween defining flow passages communicating with the inlet and open at the peripheries of the shrouds, and the peripheral edge of at least one, and more preferably both, of the shrouds including teeth between the vane outer ends.

Referring to the drawings:

FIG. I is a view in perspective of a centrifugal impeller constructed in accordance with a preferred embodiment of the invention;

FIG. 2 is an elevational sectional view of the impeller shown in FIG. 1 taken on line 22 of FIG. 1, looking in the direction of the arrows;

FIG. 3 is a reduced-size, elevational view of a toothed plate adapted for employment with the impeller of FIG. I to provide modified embodiments of the invention; and

FIG. 4 is a reduced-size, elevational view of a nontoothed plate adapted for employment in other modified embodiments of the invention.

Referring more specifically to the drawings wherein similar reference characters designate corresponding parts throughout the several views, FIGS. 1 and 2 illustrate an embodiment of the invention in the form of an impeller, designated generally as 110, which is particularly adapted to be rotatably driven in the rotary direction schematically depicted by the arrow R shown in FIGS. 1 and 2. The impeller 10 comprises front and rear shrouds 12, 14, respectively, of common diameter having inner or adjacent faces 16,18 bounding opposite sides of a therebetween cavity 20 and outer or remote faces 22, 24 external to the cavity 20. The front shroud 12 includes an integral, central, inlet hub 26 which projects outwardly from its outer face 22 and contains an inlet passage 28 communicating through an aligned, inlet opening in the shroud 12 with the center of the cavity 20. The peripheral edges of the shrouds l2, 14 define the outerperiphery of the impeller 10 and have therebetween openings or discharge passages 30, separated by lands 32, which discharge fluid from the cavity 20 in a direction radially of the impeller 10.

A plurality of arcuate vanes 34 are disposed in the cavity 20 with their opposite side faces 34a unitary with the shrouds 12, 14. The vanes 34 have inner ends 36 generally centrally of the shrouds l2, l4 arcuately spaced around the inlet opening in the front shroud 12 and outer ends 38 adjacent the peripheries of the shrouds 12, 14 arcuately spaced around such peripheries. The arcuate configuration of the vanes 34 is such that their outer ends 38 trail their inner ends 36 in the rotary direction of the impeller rotation; and the vanes 34 therebetween define the usual flow passages 40 which at their inner ends communicate with the fore mentioned inlet opening through the shroud 12 and at their outer ends are open to the openings 30 to therethrough radially discharge fluid from the impeller cavity 20.

In accordance with the present invention, the peripheral edge of each of the shrouds 12, 14 is provided with a plurality of alternate, integral teeth or vanes 42 and recesses 44 intermediate each of the adjacent ones of the vane outer ends 38 and, hence, longitudinally along each of the vanes 34. The teeth 42 are constructed with their side faces 46 in the same planes as the corresponding side faces of their shrouds 12, 14 and may be formed by broaching, cutting, casting, or any other suitable method. The roots or bottoms of the recesses 44, as shown in FIG. 2, are radially outwardly of the vanes 34 along which they are located. Also, as illustrated, the alternating teeth 42 and recesses 44 along each vane 34 are peripherally spaced from those along the adjacent vanes 34 by therebetween non-toothed portions 48 of the peripheral edges l2, l4. Alternatively, however, the entire peripheral edges of the shrouds l2, 14 could, if desired, be provided with the alternating teeth 42 and recesses 44. Moreover, although the teeth 42 and recesses 44 of each shroud l2, 14 of the impeller 10 are aligned with corresponding ones of the other shroud l2, l4, altematively, the teeth 42 and recesses 44 of each of the shrouds l2, 14 could be misaligned with those of the other.

The illustrated teeth 42 are generally of the configuration of circular saw teeth and each face in the rotary direction of the impeller rotation. More particularly, the teeth 42 each include a concave leading face 50 and a convex trailing face 52, the latter arcuately extending in the direction of the impeller rotation as it longitudinally extends from the inner end of the tooth 42 towards the outer end thereof and joining the tooth leading face 50 at a point 54 facing in the direction of the impeller rotation. The roots of the recesses 44 are similarily arcuately contoured; and hence the teeth 42 and recesses 44 cooperate to provide the shrouds l2, 14 with a waved profile at their locations. The illustrated tooth and recess configurations, although highly satisfactory in operation and believed to be preferable, are however not essential; and the teeth and recesses of the shrouds l2, 14 could, if desired, be of other, and even straight-edged, configuration; The leading edges of the non-toothed portions 48 of the impeller are provided with points 56a generally similar to the points 54 of the teeth 52.

By experimentation, it has been discovered that an impeller constructed in the configuration of the aforedescribed impeller 10 can provide a 25.5 percent increase in head at its best efficiency point and 13 percent in head at shutoff (i.e., with the discharge valve shut), while only being 2 percent lower in efficiency than a conventional full shrouded impeller wherein the peripheral edges of the shrouds are non-toothed.

FIG. 3 illustrates an annular plate 58 throughout its periphery having teeth 60 generally similar to those on the impeller 10. Such a plate 58 of diameter at least generally that of the shrouds 12, 14 may, if desired, be appended to the remote face 22, 24 of either or both of the shrouds 12, 14 of the impeller 10. In experimentation employing such an additional plate 58, substantial gains in head were found to be attained over conventional full shrouded impellers not having teeth on the peripheral edges of the shrouds; however, these gains in efficiency were not as great as the aforestated increases attainable with the impeller 10 without such plates 58.

FIG. 4 illustrates an annular plate 62, of diameter at least generally that of the shrouds 12, 14, having a nontoothed peripheral edge 64 which may also be employed in conjuncation with the impeller 10 shown in FIGS. 1 and 2 and/or the impeller modified by the plate 58 shown in FIG. 3. Experimentation employing impellers of these modified types has shown that such impellers do again provide increased heads over conventional full shrouded impellers. However, it is at least at this time believed that the form of the invention embodied by the impeller 10 shown in FIGS. 1 and 2 is more preferable.

From the preceding description it will be seen that the invention provides a new and improved impeller capable of attaining all of the aforestated objects and advantages. It will be understood, however, that, although only a few embodiments of the invention have been illustrated and specifically hereinbefore described, the invention is not limited merely to these few embodiments but rather contemplates other embodiments and variations within the scope of the following claims. Moreover, it will also be understood that, although the invention has been illustrated and hereinbefore described with regard to impellers having both front and back shrouds, it could, if desired, be incorporated in impellers having only a single shroud; or alternatively only a single shroud of an impeller having both front and back shrouds could be provided with the aforedescribed teeth and recesses.

Having thus described my invention, I claim:

l. A centrifugal impeller comprising a pair ofshrouds having a cavity therebetween and spaced at their peripheries to permit discharge from said cavity, one of said shrouds having an inlet communicating with said cavity centrally thereof, a plurality of vanes in said cavity unitary with said shrouds, said vanes extending from adjacent said inlet towards the peripheries of said shrouds and having outer ends at locations spaced around the peripheries of said shrouds, said vanes therebetween defining flow passages communicating with said inlet and open at the peripheries of said shrouds, and the peripheral edge of each of said shrouds between each of the adjacent ones of said vane outer ends including a plurality of teeth spaced by a therebetween recess.

2. A centrifugal impeller according to claim I, wherein said teeth all face in the direction of the rotation of the impeller.

3. A centrifugal impeller according to claim 2, wherein the trailing edges of said teeth extend in the direction of rotation of the impeller as they longitudinally extend towards the outer ends of said teeth.

4. A centrifugal impeller according to claim 1, wherein said teeth all face in a single direction circimferentially of said shrouds.

5. A centrifugal impeller according to claim 1, wherein said teeth at their outer ends terminate in points, said points facing in a single direction circumferentially of said shrouds.

6. A centrifugal impeller according to claim 1, wherein said vanes arcuately extend from adjacent said inlet to their said outer ends such that said teeth are located longitudinally along said vanes.

7. A centrifugal impeller according to claim 1, wherein the faces of said teeth leading in the direction of the rotation of the impeller are concave and the faces of said teeth trailing in said direction are convex.

8. A centrifugal impeller according to claim 1, further comprising a plate of diameter generally that of said shrouds adjacent to one of said shrouds external to said cavity, the peripheral edge of said plate being toothed.

9. A centrifugal impeller according to claim 1, further comprising a plate of diameter generally that of said shrouds adjacent to one of said shrouds external to said cavity, the peripheral edge of said plate being nontoothed.

10. A centrifugal impeller according to claim 1 further comprising a pair of plates of diameter generally that of said shrouds adjacent to one of said shrouds external to said cavity, the peripheral edge of one of said plates being non-toothed and the peripheral edge of the other of said plates being toothed.

11. A centrifugal impeller according to claim I, wherein the trailing edges of said teeth extend in the direction of rotation of the impeller as they longitudinally extend towards the outer ends of said teeth.

12. A centrifugal impeller comprising front and rear shrouds having adjacent side faces bounding opposite sides of a cavity between said shrouds and remote side faces external to said cavity, the peripheral edges of said shrouds defining the outer periphery of the impeller and said shrouds being at their said peripheral edges spaced by passage means permitting discharge from said cavity radially of the impeller, one of said shrouds having an inlet communicating with said cavity centrally thereof, a plurality of vanes in said cavity unitary edges of said shrouds at locations spaced therearound,

and said peripheral edges of each of said shrouds including alternating teeth and recesses longitudinally along each of said vanes and intermediate each of adjacent ones of said vane outer ends.

13. A centrifugal impeller according to claim 12, further comprising an inlet hub unitary with said one of said shrouds.

14. A centrifugal impeller according to claim 12, wherein said teeth all face in the direction of rotation of the impeller, and the trailing edges of said teeth extend in the direction of such rotation as they longitudinally extend from the inner ends of said teeth towards the outer ends thereof. I

15. A centrifugal impeller comprising a pair of shrouds having a cavity therebetween and spaced at their peripheries to permit discharge from said cavity, one of'said shrouds having an inlet communicating with said cavity centrally thereof, a plurality of vanes in said cavity unitary with said shrouds, said vanes extending from adjacent said inlet towards the peripheries of said shrouds and having outer ends at locations spaced around the peripheries of said shrouds, said vanes therebetween defining flow passages communicating with said inlet and open at the peripheries of said shrouds, and the peripheral edge of at least one of said shrouds including teeth between said vane outer ends.

16. A centrifugal impeller according to claim 15, wherein said peripheral edge of said one of said shrouds between each of the adjacent ones of said vane outer ends includes a plurality of said teeth spaced by a therebetween recess.

17. A centrifugal impeller according to claim 16, wherein said vanes arcuately extend from adjacent said inlet to said outer ends such that said teeth and recesses are located longitudinally along said vanes.

18. A centrifugal impeller according to claim 17, wherein the faces of said teeth leading in the direction of the rotation of the impeller are concave and the faces of said teeth trailing in said direction are convex. =l 

1. A centrifugal impeller comprising a pair of shrouds having a cavity therebetween and spaced at their peripheries to permit discharge from said cavity, one of said shrouds having an inlet communicating with said cavity centrally thereof, a plurality of vanes in said cavity unitary with said shrouds, said vanes extending from adjacent said inlet towards the peripheries of said shrouds and having outer ends at locations spaced around the peripheries of said shrouds, said vanes therebetween defining flow passages communicating with said inlet and open at the peripheries of said shrouds, and the peripheral edge of each of said shrouds between each of the adjacent ones of said vane outer ends including a plurality of teeth spaced by a therebetween recess.
 2. A centrifugal impeller according to claim 1, wherein said teeTh all face in the direction of the rotation of the impeller.
 3. A centrifugal impeller according to claim 2, wherein the trailing edges of said teeth extend in the direction of rotation of the impeller as they longitudinally extend towards the outer ends of said teeth.
 4. A centrifugal impeller according to claim 1, wherein said teeth all face in a single direction circimferentially of said shrouds.
 5. A centrifugal impeller according to claim 1, wherein said teeth at their outer ends terminate in points, said points facing in a single direction circumferentially of said shrouds.
 6. A centrifugal impeller according to claim 1, wherein said vanes arcuately extend from adjacent said inlet to their said outer ends such that said teeth are located longitudinally along said vanes.
 7. A centrifugal impeller according to claim 1, wherein the faces of said teeth leading in the direction of the rotation of the impeller are concave and the faces of said teeth trailing in said direction are convex.
 8. A centrifugal impeller according to claim 1, further comprising a plate of diameter generally that of said shrouds adjacent to one of said shrouds external to said cavity, the peripheral edge of said plate being toothed.
 9. A centrifugal impeller according to claim 1, further comprising a plate of diameter generally that of said shrouds adjacent to one of said shrouds external to said cavity, the peripheral edge of said plate being non-toothed.
 10. A centrifugal impeller according to claim 1 further comprising a pair of plates of diameter generally that of said shrouds adjacent to one of said shrouds external to said cavity, the peripheral edge of one of said plates being non-toothed and the peripheral edge of the other of said plates being toothed.
 11. A centrifugal impeller according to claim 1, wherein the trailing edges of said teeth extend in the direction of rotation of the impeller as they longitudinally extend towards the outer ends of said teeth.
 12. A centrifugal impeller comprising front and rear shrouds having adjacent side faces bounding opposite sides of a cavity between said shrouds and remote side faces external to said cavity, the peripheral edges of said shrouds defining the outer periphery of the impeller and said shrouds being at their said peripheral edges spaced by passage means permitting discharge from said cavity radially of the impeller, one of said shrouds having an inlet communicating with said cavity centrally thereof, a plurality of vanes in said cavity unitary with said shrouds, said vanes arcuately extending from adjacent said inlet to adjacent the peripheral edges of said shrouds and having inner ends generally centrally of said shrouds and outer ends adjacent the peripheral edges of said shrouds at locations spaced therearound, and said peripheral edges of each of said shrouds including alternating teeth and recesses longitudinally along each of said vanes and intermediate each of adjacent ones of said vane outer ends.
 13. A centrifugal impeller according to claim 12, further comprising an inlet hub unitary with said one of said shrouds.
 14. A centrifugal impeller according to claim 12, wherein said teeth all face in the direction of rotation of the impeller, and the trailing edges of said teeth extend in the direction of such rotation as they longitudinally extend from the inner ends of said teeth towards the outer ends thereof.
 15. A centrifugal impeller comprising a pair of shrouds having a cavity therebetween and spaced at their peripheries to permit discharge from said cavity, one of said shrouds having an inlet communicating with said cavity centrally thereof, a plurality of vanes in said cavity unitary with said shrouds, said vanes extending from adjacent said inlet towards the peripheries of said shrouds and having outer ends at locations spaced around the peripheries of said shrouds, said vanes therebetween defining flow passages communicating with said inlet and open at the peripheries of said shrouds, and The peripheral edge of at least one of said shrouds including teeth between said vane outer ends.
 16. A centrifugal impeller according to claim 15, wherein said peripheral edge of said one of said shrouds between each of the adjacent ones of said vane outer ends includes a plurality of said teeth spaced by a therebetween recess.
 17. A centrifugal impeller according to claim 16, wherein said vanes arcuately extend from adjacent said inlet to said outer ends such that said teeth and recesses are located longitudinally along said vanes.
 18. A centrifugal impeller according to claim 17, wherein the faces of said teeth leading in the direction of the rotation of the impeller are concave and the faces of said teeth trailing in said direction are convex. 